I. Field of the Invention
The destruction of teeth by dental caries and the loss of their support through inflammatory periodontal disease is related to the activity of microbial plaque. Although differing in particulars, the relationships are essentially identical: pathogenic microorganisms become attached to a tooth, take in nutrients and liberate chemicals that are injurious to the target site, whether tooth, periodontium, or both. The attachment of organisms can be effected by growth in the sheltered areas such as pits, fissures and faults of teeth, by self-produced adherence and colonization, such as in plaque formation, or by a combination of processes. Given sufficient nutrients and time to form toxic substances, the microorganisms will produce caries and periodontal lesions at susceptible sites.
II. Description of the Prior Art
The problem of preventing caries and inflammatory periodontal disease has been approached experimentally by attempting to interfere with plaque formation and activity and by altering tooth surfaces. Attempts to change surface characteristics of teeth to prevent colonization of microorganisms remain a problem. Alterations in the chemical rather than physical characteristics of the target site have been achieved to some extent by the exposure of the tooth surfaces to fluoride ions made available in water supply, dietary supplements, dentifrices, mouthwashes, topically applied solutions and gels, and respective materials. Unfortunately, no such simple and effective agent is available to alter the soft tissues. The most successful control of plaque related to dental caries and periodontal disease has been professional mechanical removal.
In recent past, particularly since the advances of bleaching procedures of tooth surfaces either by the in-office procedure or home treatment procedure, it is a well accepted method to mechanically remove the oral plaque formulations prior to bleaching. Voluminous studies have been conducted which indicate that plaque formulation is detrimental to the bleaching process due to the inability of the bleaching actives to penetrate easily the plaque lipoid formation and affect cosmetic effect on the tooth surfaces.
In rather simple terms, dental plaque has been described as a tenacious, soft deposit consisting chiefly of bacteria and bacterial products. More precisely, plague includes specific types of bacterial colonies surrounded by gel-like intercellular substance derived chiefly from the bacteria themselves, but also containing components from saliva and crevicular fluids, leucocites and epithelial cells. The microflora of the plaque is water insoluble and degrades the bleaching actives rapidly and must be mechanically removed prior to bleaching.
Recent bacteriological and biochemical studies of oral plaque suggest that plaque should be considered a liposome. Liposomes are self-assembled, self-closed colloidal particles in which their membrane is composed from a lipid bilayer and encapsulates a fraction of the solvent in which they are suspended. Because liposomes can entrap hydrophilic molecules into their interior, usually fermentable bacterial acids, and hydrophobic molecules into their lipophilic membrane, they have the capacity to absorb these molecules as well. Plaque liposomes, in particular the hydrophilic fermentable acids in the inner structure of the molecule, in presence of peroxidase and catalase will interact with polypeptide chains and diminish, if not totally destroy, the efficacy of the enzymes to interact with hydrogen peroxide to generate oxygen.
Hydrogen peroxide is an amphiphilic compound. It contains hydrophilic and lipophilic molecules which can readily be neutralized by the bacterial acids, usually acidic and lactic acids, that are freely produced by the polysaccharides of plaque. Therefore, it is essential that the oral cavity be relatively free of plaque accumulations prior to bleaching and whitening procedures.
The bleaching of teeth and removal of plaque has been the home care procedure most widely recommended to promote oral cleanliness and aesthetic appearance. Its basic purpose is to remove oral accumulation of plaque and debris and thereby assist in the bleaching process. Bleaching agents, such as hydrogen peroxide, carbamide peroxide, calcium peroxide, perborates and peracids, for example, are readily degraded in presence of organic matter or in the presence of abrasives that contain salts of metals, particularly transient metals. The composition of the plaque appears to be lipoidal in character and the interfacial tension between it and the tooth surfaces is quite high. As a result, in absence of an abrasive to mechanically remove the plaque accumulation, an excess amount of bleaching actives is necessary to effect bleaching. However, when hydrogen peroxide is emulsed in inclusion complex substances they have reduced water and saliva and water solubility, the amount of bleaching actives can be significantly reduced; said composition being stable over a long period of time even when contained in a single chamber, such as toothpaste tube. The oral compositions of the present invention may contain additional formulating agents such as topical local anesthetics, sweeteners, preservatives, thickeners and emulsifiers, fluoride compounds, pH adjusting compounds, humectants, flavors, colorants, surfactants, alcohols and water.
It is an object of the present invention to provide improved toothpaste bleaching composition for use in the oral cavity with improved stability.
It is also an object of the present invention to provide improved bleaching compositions for use in the oral cavity that contains inclusion complex polymers and copolymers to retard for a relatively short period of time the solubility of the bleaching actives contained within the composition and forming long lasting bleaching film on the tooth surface.
It is another object of the present invention to provide improved bleaching compositions of the type stated wherein the oral cavity is rendered relatively free of plaque accumulations prior to activation of bleaching agents contained therein.
It is yet another object of the present invention to provide oral compositions of the type stated wherein the abrasive agent is an inert bleach-stable polymer, copolymer or crosspolymer.
It is still yet another object of the present invention to provide oral compositions of the type stated wherein the bleaching actives and the abrasive agents are capable of co-containment.
It is further an object of the present invention to provide oral composition of the type stated wherein one of the bleaching active is carbamide peroxide and the other is hydrogen peroxide.
It is further yet an object of the present invention to provide an improved stable bleaching composition of the type stated wherein the carbamide peroxide composition is separated in the form of stripe or stripes from the balance of the composition comprising hydrogen peroxide actives dispersed in a main phase containing formulating aids.
It is still further an object of the present invention to provide an improved bleach stable dental composition useful in the treatment of gingivitis and in the prevention of periodontal disease.
It still yet another object of the present invention to provide an improved bleach stable dental composition of the type stated in the control of dental malodors.
It is still further yet another object of the present invention to provide an improved bleach-stable dental composition of the type stated and formed into a solid tablet that can be employed in the treatment of post-extraction necrotic socket (dry socket) to prevent pain associated with subsequent infection.
In utilizing the oral composition wherein the bleach-stable abrasive agents and the bleaching actives are formulated to be packaged in one chamber, or container, a desired amount of the composition is disposed on a toothbrush, or any other instrument, and topically applied on selected tooth surfaces and by the mechanical action of the tooth bristles the abrasive agents effectively and quickly remove the plaque accumulations from the tooth surfaces to allow the slightly action retarded bleaching agents, which are contemporaneously acted upon by the salivary enzymes catalase and peroxydase to generate free oxygen to then diffuses into the plaque-free enamel easily and quickly where it releases free radicals with unpaired electrons. These free radicals oxidize the organic matter, which causes many stains, to create lighter intermediates by cleaving carbon ring structures. As the bleaching process proceeds, double bonds in the lighter intermediates are broken and the material reaches its saturation point. Bleaching slows down dramatically when there are no longer double bonds available and the bleaching process ceases before the carbon backbones of protein are attacked which may result in the loss of enamel matrix.
The oral compositions of the present invention may comprise bleaching actives that have quick onset of activity, such as hydrogen peroxide and carbamide peroxide, that are relatively inexpensive and readily available.
In summary, peroxygens, in particular hydrogen peroxide and carbamide peroxide, when utilized as an agent for whitening and bleaching of teeth, and in presence of significant plaque accumulation, the plaque microflora releases a large amounts of acids to react with peroxidase and catalase to degrade their ability to interact with hydrogen peroxide to generate oxygen. The reduced amount of generated oxygen being lipophilic, will be attracted by the lipid plaque by the interfacial tension that exists between the two liposomes and thus prevents its diffusion into the enamel rods in search of the double-bonded stains.
Accordingly, the present invention is directed to a bleaching oral composition comprising (a) a continuous phase of water soluble, water miscible, hydrophilic composition containing an effective amount of one or more bleaching actives present in the operative range of about 0.5 percent and 55 percent with respect to the total weight of the composition, distributed, dissolved or otherwise emulsed in a composition containing inclusive complexes that are slowly water soluble polymers or copolymers in addition to sweeteners, flavors, topical anesthetics, humectants, alcohols, and other formulating adentaes and (b) uniformly dispersed throughout said continuous phase; and (b) a discontinuous phase of an effective amount of one or more bleach-stable inert polymer, copolymer and crosspolymer abrasive agents present in the operative range of about 10 percent and 75 percent with respect to the total weight of the composition.
When topically applied to tooth surfaces, the inclusion complex polymers and copolymers retard the activity of the bleaching agents sufficiently to allow the abrasive agents by mechanical action remove the plaque and pellicles from enamel surfaces thus allow for easier diffusion of the bleaching agents into the plaque and pellicle-free enamel thus allowing the bleaching active to effectively whiten the tooth surfaces. The composition of the present invention may contain additional formulating agents such as sweeteners, 0.5% to 10%; flavors, 0.5% to 15%; preservatives, 0.5% to 15%; topical anesthetics, 0.0% to 15%; thickening and emulsifying agents, 1.0% to 25%; humectants, 0.5% to 45%; buffers, to adjust the pH of the composition between 5.5 to 8.5; alcohols, 0.0% to 25%; colors, 0.0% to 15%; solvents (other than water), 0.0% to 50%; fluoride compounds, 0.0% to 5%, and water 10% to 80%.
Other objects and advantages of the present invention will be apparent to those skilled in the art on reading the following disclosure, and therefore, the invention includes the new and novel compositions and processes of making and using compositions herein illustrated.